The intent of this post is to get some recommendations for online parts sources in the U.S. - and a story.
The tldr; part ...
Last month I ordered an engine air filter and a cabin air filter from a fairly well known online parts retailer. Pretty standard stuff, logged in, placed order, completed checkout, received confirmation and a day later got tracking information. A package on time from the parts store, but instead of two filters, it contained a radiator fan shroud. <sarcasm> I can see how you can get two air filters confused with a fan shroud. </sarcasm>

Of course this happens on a Friday and by the time I get home to discover the error, they are already closed for the weekend. I put in a return request with the reason. Monday they ask for a picture. They issued a return shipping label and promise to ship out the correct parts as soon as they receive the wrong one. Fair enough, I suppose. A week after they had received the fan shroud (I verified by tracking number it was delivered) I contacted them again asking if they had sent out the correct items from the original order.
Here's where it gets a little wonky. The response I got was
"It looks like USPS has not updated the tracking from the second shipment we will try an email them for an update" 
. This didn't seem quite right, so I asked for the tracking number. The next day they send me a tracking number showing the ship date as that day, not a week earlier. So they either forgot to ship it, lied to me about shipping it and then shipped it, or they did ship it, the post office lost it and they sent a 2nd replacement order. Given that they didn't have a tracking number for the order they said was lost, I'm going with the former. Hey, but at least it shipped.
So a few days later the package arrives containing the cabin air filter that I ordered and an engine air filter for a Mitsubishi Mirage

. Since I already had a thread going with their customer service I let them know about the wrong part. The response was
"We do apologize we do not know what happened with the second order I will make sure and personally send the correct one out today". That was Monday. Still no package or tracking number as of today (Friday).
Right now I have no idea if they will actually send me the right filter, forget about it again, or mail me a live badger. It's equal odds at this point.
So... who should I buy from?